High wattage contactor

ABSTRACT

One hundred amps. or more is switched with limited space requirements and easy access to parts. A coil bobbin of phenolic or the like serves as a guide for a magnetically responsive armature or plunger. The taper and mushroom head on this armature allows the magnetic attraction of the coil to be used more than would be the case if the head were cut off at right angles. The armature is actually guided by the bobbin and operates therein with dashpot action. The contacts are preferably plated with silver cadmium oxide designed with double break so that no pigtails are required. There is high capacity for overload with little or no corrosion, the springs being stainless steel and the frames plated. An interlock switch is separately fabricated and attached in position for use, all terminals, springs, nuts and other parts being readily accessible from the front of the device.

United States Patent 1 1 McFarlln HIGH WATTAGE CONTACTOR [75] Inventor:William B. McFarlin, Wauwatosa,

Wis.

[73] Assignee: Stearns Electric Corporation,

Milwaukee, Wis.

[22] Filed: Dec. 29, 1971 211 Appl. No.: 213,375

(451 Apr. 23, 1974 Primary ExaminerHarold Broome Attorney, Agent, orFirmWheeler, Morsell, House & Wheeler [5 7] ABSTRACT One hundred amps.or more is switched with limited space requirements and easy access toparts. A coil bobbin of phenolic or the like serves as a guide for amagnetically responsive armature or plunger. The taper and mushroom headon this armature allows the magnetic attraction of the coil to be usedmore than would be the case if the head were cut off at right angles.The armature is actually guided by the bobbin and operates therein withdash'pot action. The contacts are preferably plated with silver cadmiumoxide designed with double break so that no pigtails are required. Thereis high capacity for overload with little or no corrosion, the springsbeing stainless steel and the frames plated. An interlock switch isseparately fabricated and attached in position for use, all terminals,springs, nuts and other parts being readily accessible from the front ofthe device.

15 Claims, 4 Drawing F lgures PATENTED APR 23' I974 HIGH WATTAGECONTACTOR BACKGROUND OF INVENTION The foregoing advantages are achievedby the disclosed construction in which a contactor in the nature of arelay has magnetic coils wound on a dielectric tube which serves both asa guide and as a dashpot for an armature having a mushroom head. Thearmature is supported on a stainless steel spring. An interlock or otherauxiliary switch may optionally be used with ready access.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a plan view of a heavy dutyswitch embodying the invention.

FIG. 2 is a front elevational view thereof with an auxiliary interlockswitch.

FIG. 3 is aview in side elevation of the assembly shown in FIG. 2partially broken away to vertical cross section.

FIG. 4 is a view in relatively separated positions of parts of theassembly as such parts appear in FIG. 3.

DETAILED DESCRIPTION It is one of the features of the disclosed devicethat it may be mounted in various positions without rendering nuts orbolts inaccessible. High thermal-capacity coils 6 are carried on abobbin 8 which may conveniently be made of phenolic material with anintegral dowel 10 received in the hole 12 of a plate 14 which isfastened to the frame member 16. Closure 32 and bearing 84 arepermanently attached to plate 14. The frame 16 may be mounted in avariety of positions, being screwed to a mounting plate 18 as shown inFIG. 3. The plate 18 has keyhole slots 1, 2' and 3 as best'shown in FIG.2. Regardless of the way in which the plate is mounted, the dowelmaintains proper orientation of the terminals of the coil or coils 6.

Attached to that portion of the frame which is uppermost in FIG. 1 is aphenolic mounting block 20 which has a socket 22 for the mushroom head24'0f the armature 26. This armature is guided for reciprocation in thecore 28 of the bobbin. The fit is close enough so that the core providesdashpot action for the armature 26. The smoothness of such action isenhanced by the provision of a head 30 which, instead of being squarecut, has the form of a truncated cone for which the closure has acomplementary seat 32 FIG. 3). The form is such that the head 30approaches the closure 32 with graduated electromagnetic response. Theelectromagnetic response is enhanced initially by the truncated conehead 30 and then by mushroom head 24 as the head 24 approaches themagnetizable frame portions The stainless steel armature spring 34 isguided on a rod 36 which extends and is threaded through the armatureand is housed in opening 40 in the lower part of the armature. The rod36 is guided by bearing 84.

The flange 44 at the upper end of the armature carries a nut 46 andsupports a headed fitting insulator 48 and steel pivot washer 82. Arockable sleeve 50 on a transverse fulcrum rib 52 (FIG. 4) rests againstwasher 82. The bridge 55 carries contacts 56 which are preferably madeof silver cadmium oxide or the like to insure continuity, resistcorrosion and have strong anti-weld characteristics. The design is suchthat these contacts are fully exposed for inspection and this is trueregardless of the position in which the contactor is mounted. The rib 52permits the contact arms and contacts to adjust themselves to a goodseat.

Considerable importance is attached to details of the construction shownin FIGS. 3 and 4 which is intended to eliminate or minimize adjustmentswhich might otherwise be required following replacement of parts.Already described is the rod 36 which extends centrally through the core28 of the bobbin. Together the rod and bobbin core guide the armature 26for which compression spring 34 provides resilient support. The head 30of armature 26 is tapered, having the form of a truncated cone, forwhich the bottom closure 32 has a complementary taper such that the headapproaches the closure with graduated electromagnetic response.

The guidance of the cone for the armature 26 is sufficiently close toprovide substantial dashpot control enhanced in the final movement ofthe core as the mushroom head 24 approaches the non-magnetic stainlesssteel washer 81 in the bottom of the cavity 22 in which the mushroomhead 24 operates.

On top of the frame 16 is the block of insulating material 20 which maybe phenolic or the like and which may be made up of several sections,the total being generally L-shaped in vertical cross section (FIG. 3).Forwardly projecting from this block at its rear are contact carryingarms 19 and 21, respectively provided with contact bolts 57 for thecontacts 58. Assuming that the switch is normally closed as in thespecies herein illustrated, a contact carrying bridge 55 is mounted onsleeve (FIG. 4).

The electric terminals 19 and 21 spaced from each other behind thearmature, register with the contacts 56 at the end of bridge 55. Alsospaced to register with contacts 56 are the contacts 60 on terminals 62,63, which lie below the level of the bridge (FIG. 2).

As indicated, the bridge is supported to project laterally from sleeve50 having an inturned shoulder 98. Within the sleeve there is acompression spring 66 (FIG. 4). One end of spring 66 bears against thebottom of the sleeve 50 and within that end is the reduced neck of theinsulator 48 having an outturned flange 90. Another insulator 64 has aneck portion extending into the upper end of spring 66 and fitted intothe top of sleeve 50 (FIG. 3). When the nut 67 threaded to the upperendof shaft 36 is tightened to draw the ends of insulators and 64together as shown in FIG. 3, the adjustment becomes proper and thedownward pressure from arm 21 to the bridge 55 is correct. When thecontacts 56 engage the contacts 60, the springseat 94 on the insulator64 moves within the sleeve 50 until the mushroom head oroutwardlyextending annular flange 44 engages the washer 81. The predeterminedtravel thus afforded of the rod 36 and armature 26 after engagement ofthe contacts 56 and determines the normally opencontact wear allowanceand contact presing against insulator 48, the insulator 64 assists inguiding the threaded rod 36 and in establishing the proper springpressure to which the armature is subject when the nut 67 is adjusted.It also, of course, insulates the armature rod 36.

Mention has been made of the fact that the assembly of parts describedeliminates the need for the individual adjustment for such parts, sincethe adjustment is automatically achieved during assembly. Thus, when thenut 67 at the top of rod 36 is tightened, the insulator spring seat 64compresses spring 66 to the correct contact spring pressure to whichcontacts 60 should be subject. Thus, when the bridge assembly 55 isreplaced in service and the parts are re-assembled, the correctpressures are automatically achieved and need for adjustment iseliminated.

The insulating rod 36 and the assembly of coil 6 thereon automaticallyinsulates the coil from the frame member 16 and results in the fact thatthe mounting plate 18 is electrically dead so that the device can bemounted to steel or any other surface without the use of insulatingmaterials other than those already present in the assembly.

The contactor as shown is a double throw switch, one side being normallyopen and one normally closed. The contacts 58, which provide thenormally closed circuit, may be replaced with normally open contacts,and the contacts 60 can be replaced with normally closed contacts,whereby the switch is changed from normally closed to normally open.When re-assembled, it will function as desired without requiring otheradjustment.

The mushroom head 24 stops against the nonmagnetic washer 81 to allowthe armature to drop out without residual magnetism when the coil isdeenergized.

The contactor which includes the bridge 55 interrupts the electricalcircuit in two places, providing a double break instead of a singlebreak such as would be provided but for the construction shown. Thisgreatly enhances the electrical life by disrupting the arcing abilitywhich the moving contactor would otherwise have. Moreover, the contactsare clearly visible from the front, thus facilitating visual inspection.The coil 6 operates at a much lower temperature than otherwise becausethe heat generated is conducted physically away from the coil throughthe plate 14 into frame member 16 to the mounting plate 18, which thusprovides a heat sink.

Above and below each of the contacts 56 there are contacts 58 and 60. Inthe illustrated embodiments, the electromagnetically operated contacts56 are normally seated under the bias of spring 34 against fixedcontacts 58. Subject to the magnetic response of the armature 26,contact 56 may engage the normally open contacts 60. To absorb shock,the assembly 50 is not fixed solidly to the rod 36 but is supported bymeans of compression spring 66 on an insulator 64.

It is particularly to be observed that all of the nuts and screws usedto assemble the described parts are readily accessible from the front,as shown in FIGS. 1 and 2. All terminals and mounting holes areaccessible from the front.

If desired, an accessory device such as an electrical interlock switch75 may be hung on the frame. This switch per se forms no part of thepresent invention and consequently is not illustrated in detail. It is aconventional commercial switch having an actuator or contact button 76,a mounting bracket 78 and a spring arm 80 which may be attached, as bestshown in FIG. 3, to the reciprocable rod 36 to project over the switchactuator 76 for engagement therewith when the armature 26 and itscentral rod 36 are displaced in a direction which is downward, as viewedin FIG. 3.

It will be understood in this connection that the design of theapparatus is such that it will function either vertically orhorizontally or otherwise. It is not, therefore, to be regarded asrequiring a mounting in the position shown.

In order to provide maximum disclosure of the most desirableconstruction and material known to me, I have specified many details ofconstruction and materi als which, for some purposes, may not berequired. I do not, therefore, wish to limit my definition of theinvention except by reference to the accompanying claims. Long wear isassured by the use of non-corrosive contacts, absence of pigtails, theability of the switch to handle heavy overloads without injury, makingthe springs of stainless steel, and plating the frame. The specificembodiment as shown and described has been tested for a mechanical lifeof five million operations within an electrical life of three millionoperations. Notwithstanding its heavy duty construction, it requiressmaller paneled area than any commercial device for this prupose whichis known to me. In practice, it requires less than twelve square inchesper mounting. It uses a minimum number of major parts in itsconstruction.

I claim:

l. A contactor comprising a coil bobbin having a tubular core and awinding thereon supported on a frame, a fixed electrical contact on saidframe, an armature guided for axial reciprocation in said core andprovided with a mushroom head at one end and a truncated cone at theother end, an electrical contact movable with said armature, and meansproviding a complementary closure for the bobbin and with which saidarmature coacts, and magnetizable frame portions in the path of travelof said mushroom head for magnetically attracting said mushroom headwhen said coil is energized, said mushroom head providing increasedmagnetic attraction of said armature'with said coil and saidmagnetizable frame portions as said head approaches said magnetizableframe portions and said armature contact engages said fixed contact tocomplete an electric circuit.

2. A contactor according to claim 1 including a nonmagnetic washerbetween said frame portions and said mushroom head to prevent contact ofsaid head and said frame portions to isolate said head from said frameportions and prevent residual magnetism developing in said mushroomhead.

3. A contactor according to claim 1 including a frame having means forengaging and supporting said bobbin, said bobbin having a closureelement complementary to said armature and .toward which said armatureis magnetically attracted when the coil of the bobbin is energized, saidarmature interfitting in the bobbin core to provide a dashpot actionand, additionally, to provide a graduated electromagnetic response.

4. A contactor according to claim 1 in which a mounting frame supports abobbin and has a socket for which the bobbin provides an integral dowel,said wind ing having terminal means maintained in orientation byengagement of the dowel with the socket.

5. A contactor according to claim 1 in which the frame has a dielectricmounting block, a rod extending therethrough axially of the bobbin, thearmature being mounted on the rod and fitted within the core of thebobbin, means supporting the rod for yielding resilient movement withrespect to the mounting block, and a spring of relatively non-magneticmetal disposed interiorly of the armature and engaged with the armatureand supported on a closure with which the bobbin is provided. I

6. A contactor according to claim 5 in which the armature has its saidmushroom head at the end away from which it is electromagnetically urgedwhen the coil is energized, the armature being made fast to said rod andhaving contact means movable with the armature and for which said frameprovides coacting contacts.

- 7. A contactor according to claim 6 in which said contact meansinclude at least one fixed contact toward which the said first mentionedcontact means moves when the coil is energized and another contactmeansaway from which it moves when the coil is energized.

8. A contactor according to claim 5 in which an auxiliary contactor ismounted on the frame and has a contact actuator in the path of operatingmeans with which said rod is provided.

9. A contactor according to. claim 6 in which the contact means ismovable with the armature and the said coacting contacts of the frameare normally open and the relatively non-magnetic spring automaticallymaintains proper contact pressure resistance and wear allowance isautomatically accomplished without the need for adjustments. g

10. A contactor according to claim 7 in which one of said contacts has apivotal mounting which is selfalignable when it engages another of thecontacts.

11. A contactor in accordance with claim 1 wherein said mushroom head isin the form of an outwardly extending flange.

12. A contactor comprising a mounting plate, arms projecting therefrom,an insulating bobbin supported on said arms forwardly of the plate, awinding on the bobbin, an armature reciprocable through the bobbin andprovided with a mushroom head and a terminal truncated cone, thetruncated head having acavity opening into the interior of, thearmature, a compression spring within the cavity in supporting relationto the armature, means providing a seat for the spring, a rod extendingfrom the cavity through the armature and providing guidance therefor,the armature being closely fitted within the bobbin for dashpot action,a pair of insulating elements arranged on the rod, a spring throughwhich the rod extends and which is confined thereon between saidelements, a sleeve enclosing the spring and portions of the elements,said elements being in abutment under compression of a nut with whichsaid rod is provided. I

13. A contactor comprising a frame including a mounting plate, armsprojecting therefrom, a bobbin supported on said arms forwardly of theplate, a winding on the bobbin, an armature reciprocable through thebobbin, a rod extending through the armature and providing guidancetherefor, a compression spring arranged around the rod in supportingrelation to the armature, means providing a seat for the spring, a pairof insulating elements on the rod, a second spring through which the rodextends and which is confined thereon between said elements, a sleeveenclosing the spring and portions of the elements, fulcrum means on saidsleeve engaged with one of said elements, said elements being inabutment under compression of a nut with which said rod is provided, abridge extending laterally from said sleeve and havingspaced electricalcontacts on said bridge with said bridge electrically connectirig saidbridge contacts, a pair of fixed contacts supported on said frame andspaced to engage said bridge contacts to provide a double contact anddouble break in a single conductor, and said spring and said fulcrummeans affording angular deflection of said bridge to insure engagementof said bridge contacts with said fixed contacts notwithstanding wear ormisalignment of any of said contacts.

14. A contactor in accordance with claim 13 including a second nutthreaded on said rod and engaged with said armature to secure thearmature to said rod, and one of said insulating elements having aflange with a surface abutting said second nut, and wherein said fulcrummeans includes a washer supported on an opposed surface of said nut anda radial rib on said sleeve pivotally supported on said washer andwherein said spring yields to afford a predetermined travel of said rodand said armature relative to said bridge after engagement of saidbridge contacts and said fixed contacts to compensate for wear of saidcontacts and insure engagement of said contacts notwithstanding wear ofsaid contacts.

15. A contactor comprising a coil, a coil bobbin having a tubular coreand a winding thereon, an armature guided for axial reciprocation insaid core, a frame for supporting said coil bobbin, a rod extendingtherethrough axially of the bobbin, the armature being mounted on therod and fitted within the core of the bobbin, a spring disposedinteriorly of the armature and engaged with the armature and supportedon a closure with which the bobbin is provided,'a sleeve arranged aroundsaid rod and movable with said armature, an inturned shoulder on saidsleeve, a bridge on said sleeve extending laterally in two directionsfrom said sleeve, two electrical contacts on said bridge, fixed contactson said frame disposed to engage said bridge contacts and connectable toafford a double break in a circuit, means supporting said sleeve toyieldably afford engagement of said bridge contacts and said fixedcontacts upon energization of said armature and afford angulardisplacement of said bridge relative to said rod upon engagement toinsure alignment and engagement of said bridge contacts with said fixedcontacts notwithstanding wear of any of said contacts, said means supporting said sleeve including a first insulative element having a flangeand a hollow shank, said sleeve being supported on said first elementflange, a second insulative element having a seat, a flange and a hollowshank, said rod extending through said elements, a nut threaded on therod clamping said elements in abutting engagement, a spring arrangedaround said element shanks and located between said inturned shoulder onsaid sleeve and said seat on said secondelement, with said springcompressing upon energization of said coil and movement of said armaturewhen said contacts engage as said insulative elements move relative tosaid sleeve.

1. A contactor comprising a coil bobbin having a tubular core and awinding thereon supported on a frame, a fixed electrical contact on saidframe, an armature guided for axial reciprocation in said core andprovided with a mushroom head at one end and a truncated cone at theother end, an electrical contact movable with said armature, and meansproviding a complementary closure for the bobbin and with which saidarmature coacts, and magnetizable frame portions in the path of travelof said mushroom head for magnetically attracting said mushroom headwhen said coil is energized, said mushroom head providing increasedmagnetic attraction of said armature with said coil and saidmagnetizable frame portions as said head approaches said magnetizableframe portions and said armature contact engages said fixed contact tocomplete an electric circuit.
 2. A contactor according to claim 1including a non-magnetic washer between said frame portions and saidmushroom head to prevent contact of said head and said frame portions toisolate said head from said frame portions and prevent residualmagnetism developing in said mushroom head.
 3. A contactor according toclaim 1 including a frame having means for engaging and supporting saidbobbin, said bobbin having a closure element complementary to saidarmature and toward which said armature is magnetically attracted whenthe coil of the bobbin is energized, said armature interfitting in thebobbin core to provide a dashpot action and, additionally, to provide agraduated electromagnetic response.
 4. A contactor according to claim 1in which a mounting frame supports a bobbin and has a socket for whichthe bobbin provides an integral dowel, said winding having terminalmeans maintained in orientation by engagement of the dowel with thesocket.
 5. A contactor according to claim 1 in which the frame has adielectric mounting block, a rod extending therethrough axially of thebobbin, the armature being mounted on the rod and fitted within the coreof the bobbin, means supporting the rod for yielding resilient movementwith respect to the mounting block, and a spring of relativelynon-magnetic metal disposed interiorly of the armature and engaged withthe armature and supported on a closure with which the bobbin isprovided.
 6. A contactor according to claim 5 in which the armature hasits said mushroom head at the end away from which it iselectromagnetically urged when the coil is energized, the armature beingmade fast to said rod and having contact means movable with the armatureand for which said frame provides coacting contacts.
 7. A contactoraccording to claim 6 in which said contact means include at least onefixed contact toward which the said first mentioned contact means moveswhen the coil is energized and another contact means away from which itmoves when the coil is energized.
 8. A contactor according to claim 5 inwhich an auxiliary contactor is mounted on the frame and has a contactactuator in the path of operating means with which said rod is provided.9. A contactor according to claim 6 in which the contact means ismovable with the armature and the said coacting contacTs of the frameare normally open and the relatively non-magnetic spring automaticallymaintains proper contact pressure resistance and wear allowance isautomatically accomplished without the need for adjustments.
 10. Acontactor according to claim 7 in which one of said contacts has apivotal mounting which is self-alignable when it engages another of thecontacts.
 11. A contactor in accordance with claim 1 wherein saidmushroom head is in the form of an outwardly extending flange.
 12. Acontactor comprising a mounting plate, arms projecting therefrom, aninsulating bobbin supported on said arms forwardly of the plate, awinding on the bobbin, an armature reciprocable through the bobbin andprovided with a mushroom head and a terminal truncated cone, thetruncated head having a cavity opening into the interior of thearmature, a compression spring within the cavity in supporting relationto the armature, means providing a seat for the spring, a rod extendingfrom the cavity through the armature and providing guidance therefor,the armature being closely fitted within the bobbin for dashpot action,a pair of insulating elements arranged on the rod, a spring throughwhich the rod extends and which is confined thereon between saidelements, a sleeve enclosing the spring and portions of the elements,said elements being in abutment under compression of a nut with whichsaid rod is provided.
 13. A contactor comprising a frame including amounting plate, arms projecting therefrom, a bobbin supported on saidarms forwardly of the plate, a winding on the bobbin, an armaturereciprocable through the bobbin, a rod extending through the armatureand providing guidance therefor, a compression spring arranged aroundthe rod in supporting relation to the armature, means providing a seatfor the spring, a pair of insulating elements on the rod, a secondspring through which the rod extends and which is confined thereonbetween said elements, a sleeve enclosing the spring and portions of theelements, fulcrum means on said sleeve engaged with one of saidelements, said elements being in abutment under compression of a nutwith which said rod is provided, a bridge extending laterally from saidsleeve and having spaced electrical contacts on said bridge with saidbridge electrically connecting said bridge contacts, a pair of fixedcontacts supported on said frame and spaced to engage said bridgecontacts to provide a double contact and double break in a singleconductor, and said spring and said fulcrum means affording angulardeflection of said bridge to insure engagement of said bridge contactswith said fixed contacts notwithstanding wear or misalignment of any ofsaid contacts.
 14. A contactor in accordance with claim 13 including asecond nut threaded on said rod and engaged with said armature to securethe armature to said rod, and one of said insulating elements having aflange with a surface abutting said second nut, and wherein said fulcrummeans includes a washer supported on an opposed surface of said nut anda radial rib on said sleeve pivotally supported on said washer andwherein said spring yields to afford a predetermined travel of said rodand said armature relative to said bridge after engagement of saidbridge contacts and said fixed contacts to compensate for wear of saidcontacts and insure engagement of said contacts notwithstanding wear ofsaid contacts.
 15. A contactor comprising a coil, a coil bobbin having atubular core and a winding thereon, an armature guided for axialreciprocation in said core, a frame for supporting said coil bobbin, arod extending therethrough axially of the bobbin, the armature beingmounted on the rod and fitted within the core of the bobbin, a springdisposed interiorly of the armature and engaged with the armature andsupported on a closure with which the bobbin is provided, a sleevearranged around said rod and movable with said armature, an inturnedshoulder on said sleeve, a bridge on said sleeve extenDing laterally intwo directions from said sleeve, two electrical contacts on said bridge,fixed contacts on said frame disposed to engage said bridge contacts andconnectable to afford a double break in a circuit, means supporting saidsleeve to yieldably afford engagement of said bridge contacts and saidfixed contacts upon energization of said armature and afford angulardisplacement of said bridge relative to said rod upon engagement toinsure alignment and engagement of said bridge contacts with said fixedcontacts notwithstanding wear of any of said contacts, said meanssupporting said sleeve including a first insulative element having aflange and a hollow shank, said sleeve being supported on said firstelement flange, a second insulative element having a seat, a flange anda hollow shank, said rod extending through said elements, a nut threadedon the rod clamping said elements in abutting engagement, a springarranged around said element shanks and located between said inturnedshoulder on said sleeve and said seat on said second element, with saidspring compressing upon energization of said coil and movement of saidarmature when said contacts engage as said insulative elements moverelative to said sleeve.